In order to maintain and improve good end user performance, application and system managers must understand the current performance of their applications, be able to identify and predict current and future performance problems, and evaluate potential solutions to those problems. Data such as utilizations by device, especially at major servers can be easily collected by an enterprise-wide resource monitor or other monitors. But much of the system data necessary to predict bottlenecks are not easily measurable or in some cases are not measurable at all. In this situation, these utilizations must be calculated.
Generally, utilizations increase roughly linearly with load. Other enterprise wide factors such as response times also increase with the load of the system, but these increases do so non-linearly. Since a response time in the network may become unacceptable before utilizations and vice versa, a need exists to determine a bottleneck device in the network and to change the configuration of the network to remove or replace the bottleneck device.
One commonly used network is a network of M/M/1 queues. A single M/M/1 queue is made of a Poisson arrival process, a First In First Out (FIFO) queue of unlimited capacity and a server with exponentially distributed service time. An M/M/1 queue has a traffic rate or utilization ρ. The value of ρ shows how “busy” that device or server is. The network (of M/M/1 queues) is also described by certain parameters: the rate of arrivals to the network, the visit ratio for each device (the average number of times that each request arriving to the network visits that device), and the average service time at each device. These network parameters are used to compute the utilization, the mean number of jobs in the network, and the mean network response time for the purposes of predicting bottlenecks. However, when these parameter values are not measurable, the utilization, mean number of jobs in the network, mean network response time, and bottlenecks cannot be predicted.
The prior art discloses method and apparatus for allocation of resource in a United States Publication to Liao et. al. US2004/0136379A1 and a system and method for evaluating resource utilization to Shiramizu et al. U.S. Pat. No. 5,475,844. However, the prior art does not address all of the concerns presented herein.
A need exists for a method to predict these network usage data, and identify bottlenecks from limited measurable inputs such as individual device utilizations. Also useful is the ability of a method to measure or estimate network response times by business function.